This application claims the benefit of Japanese Patent Application Number 2004-277886 filed on Sep. 24, 2004, the entirety of which is incorporated by reference.
1. Field of the invention
The present invention relates to a cutting tool, such as a cutter which cuts a workpiece with a circular cutting blade or a circular saw.
2. Description of the Related Art
A conventional circular saw has a base which is rectangular in a plain view and a main body provided on the base and having a circular saw blade (cutting blade) driven to rotate by a motor. With a condition that the saw blade protrudes below the base, the base is slid on the workpiece, whereby the workpiece is cut by the saw blade. In this circular saw the front end of a blade case covering the upper part of the saw blade is rotatably mounted to the base. On the other hand, the rear end of the blade case can be fixed at an arbitrary position along an arcuate depth guide standing on the base. In this configuration, an amount of protrusion of the saw blade (cutting depth) from the base can be adjusted by changing the engaged position with respect to the depth guide.
In this kind of circular saw, during cutting operation chips generated from the workpiece flow out to cause a problem of recognizing a black cut line, which deteriorates the working environment. In order to solve the above problem, as described in the Japanese laid-open utility model publication No. 5-5332 and the Japanese laid-open patent publication No. 11-58305, technology is applied in which a blade case covering the upper part of a saw blade is provided with the main body. For details, the blade case is provided with a dust collection route which guides chips backward along the circumference of the saw blade and discharges the chips from the exhaust port provided at the rear side of the blade case, thereby preventing the chips from being dispersed.
In such a dust collection route, since chips are easily clogged in the dust collection route, the route has to be wide in order to prevent the clogging. Because of this, a large blade case is required, which obstructs downsizing of the main body and deteriorates usability. In addition, in a circular saw having a depth guide for adjusting the cutting depth, the depth guide is generally housed in the blade case to prevent the deterioration of the appearance. That is, when the depth guide is provided at the outside of the blade case, increased convex or concave parts might be observed. Since the depth guide is housed in the blade case, the airflow generated by rotation of the saw blade could be disturbed by the depth guide, which lowers the dust collecting operation. Further, another problem occurs, that is, chips might be scattered during cutting depth adjustment as they are adhered to the depth guide.
In order to solve the above problems, an object of the present invention is to provide a cutting tool maintaining a compact-sized main body while ensuring excellent usability and dust collecting operation.